Happy Thursday! – 10/23 The diagram below represents a plant cell. Which process takes place in structure A? A cellular respiration B heterotrophic nutrition C digestion of fats D protein synthesis

Happy Friday! – 10/24 A population of long-necked giraffes shares a habitat with a second population of organisms that eat the leaves of low-growing vegetation. A scientist speculates that if the second population leaves the area, the giraffe population could exhibit shorter necks over time. Which mechanism could result in the giraffe population exhibiting shorter necks? A The long-necked giraffes would breed with a short-necked species. B Giraffes with a genetic mutation for short necks would survive and reproduce. C The presence of food on shorter plants would lead to a relaxation of giraffe necks. D Giraffes would learn to bend their necks while feeding, causing a shortening of neck muscles.

Everything must evolve…

Why do we accept this as a Scientific Theory? What is Evolution? changes in living organisms over time explains how modern organisms have descended from ancient organisms Why do we accept this as a Scientific Theory?

Evolution What we know, so far…. Many different species alive today All life shares common characteristics The Earth is very old Life is very old Life has changed over time The changes have been little changes over long periods of time Evolution But how does this work?

Evolution explains Unity & Diversity Evolution shows how organisms can be similar and how organisms can be different

Charles Darwin Father of Evolution Proposed a way how evolution works How did creatures change over time? by natural selection Collected a lot of evidence to support his ideas 1809-1882 British naturalist What did Darwin say? What evidence supports Evolution by Natural Selection? What impact did Evolution have on biology?

Voyage of the HMS Beagle Invited to travel around the world 1831-1836 (5 year journey!!) records many observations of nature and took notes & drew pictures in hundreds of notebooks After graduation Darwin was recommended to be the conversation companion to Captain Robert FitzRoy, preparing the survey ship Beagle for a voyage around the world. FitzRoy chose Darwin because of his education, his similar social class, and similar age as the captain. Darwin noted that the plants and animals of South America were very distinct from those of Europe

Voyage of the HMS Beagle Stopped in Galapagos Islands 500 miles off coast of Ecuador The origin of the fauna of the Galapagos, 900 km west of the South American coast, especially puzzled Darwin. On further study after his voyage, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland. It seemed that the islands had been colonized by plants and animals from the mainland that had then diversified on the different islands

Darwin found… many unique species Many of Darwin’s observations made him wonder… Why? Darwin asked: Why were these creatures found only on the Galapagos Islands?

Darwin found… clues in the fossils present day Armadillos Darwin found: Evidence that creatures have changed over time ancient Armadillo Darwin asked: Why should extinct armadillos & modern armadillos be found on same continent?

Darwin found: Different shells on tortoises on different islands Darwin asked: Is there a relationship between the environment & what an animal looks like?

The finches clinched it for Darwin

From 1 species to 14 species… Warbler finch Woodpecker finch Small insectivorous tree finch Large insectivorous Vegetarian Cactus finch Sharp-beaked finch Small ground finch Medium ground finch Large ground Insect eaters Bud eater Seed eaters Cactus eater Warbler Tree finches Ground finches natural selection for best survival & reproduction variation

Darwin’s Finches Darwin’s conclusions: 1. Variations in beaks differences in beaks in the original flock adaptations to foods available on islands 2. Natural selection for most fit over many generations, the beak adaptations allowed survivors to create the population diversity 3. Offspring inherit successful traits Best adaptations allow offspring to out-compete others and survive to reproduce 4. This creates new species over time

Earlier ideas on Evolution LaMarck evolution by acquired traits Organisms change their adaptations through use Give those new adaptations to their offspring example in reaching higher leaves giraffes stretch their necks & give the acquired longer neck to offspring not accepted as valid

Darwin’s view of Evolution giraffes that already have long necks survive better leave more offspring who inherit their long necks variation selection & survival reproduction & inheritance of more fit traits 

What is Natural Selection? Competition for food, mates, nesting sites, escape predators Fitness = having the right adaptations to out-compete others Survival of the Fittest = organisms with the “best” traits/adaptations survive to reproduce

Survival & Reproduction of the fittest not the biggest… …the fittest! not the fastest… not the bravest… not the strongest… Adaptations the traits that help an organism fit the environment better to survive & reproduce

Descent With Modifications Darwin concluded: Each species has descended, with changes, from other species over time. Darwin called this… Descent With Modifications or evolution (change in population over time)